Truck and trailer rules in New Hampshire: commercial vehicle line, trailer brakes, safety chains, size and weight limits

This page reports what the official source says. It is not legal advice: ask the office named here. The sources are three chapters of Title XXI Motor Vehicles of the New Hampshire Revised Statutes Annotated, published on the General Court website: chapter 259 on words and phrases, chapter 263 on drivers' licenses and chapter 266 on equipment, size and weight. Federal background and the other places are on the parent page, trucks and trailers for tree work.

At a glance

Item	What the sources say
Commercial motor vehicle	Rating of 26,001 pounds or more; or a combination rated or weighing 26,001 pounds or more that includes a towed unit over 10,000 pounds
Commercial licence classes	The commissioner sets the classification system by rule; the statute names no classes
Trailer brakes	Adequate brakes on every trailer; exception for a trailer under 3,000 pounds gross when the axle weight stays within 40 percent of the towing vehicle's rated axle weights
Safety chain	Required on every trailer in addition to the tow-bar; ultimate strength at least equal to the trailer and load weight
Width, height	102 inches wide; 13 feet 6 inches high
Length	45 feet single unit; 53 feet for a semi-trailer; 28 feet each for two trailing units
Gross weight, two axles	33,400 pounds off the interstate
Carrier rules	Federal motor carrier safety rules adopted by the commissioner of safety, with intrastate driver examinations

The commercial vehicle line and licences

RSA 259:12-e defines a commercial motor vehicle as a motor vehicle or combination used in commerce to carry passengers or property that has a gross vehicle weight rating of 26,001 pounds or more, or a gross combination weight rating or actual weight of 26,001 pounds or more including a towed unit with a rating or weight of more than 10,000 pounds. A vehicle built or used for 16 or more passengers, and a vehicle of any size carrying placarded hazardous materials, also count. The definition leaves out fire service vehicles, recreational vehicles, military vehicles driven by military personnel and vehicles used only for farming within 150 miles of the owner's farm.

RSA 263:92 says the commissioner may adopt rules for a commercial driver license classification system with the endorsements and restrictions needed to meet federal and state law, and that a driver who breaks the classification rules faces a fine of US$100. RSA 263:93 says a commercial driver license expires on the licensee's birthdate in the fifth year after issue. The class letters are not in the chapter read. See RSA chapter 263 on drivers' licenses and RSA chapter 259 on words and phrases.

Brakes and safety chains

RSA 266:27 says every motor vehicle must have adequate brakes in good working order, sufficient to control it at all times. RSA 266:27-a requires a parking brake system adequate to hold a vehicle or combination on any grade under all loads. RSA 266:28 says a motor vehicle, or a combination with a trailer or semi-trailer, must at 20 miles per hour be able to stop within 30 feet on dry, smooth, approximately level pavement with the service brake.

RSA 266:30 says no trailer or semi-trailer may be driven unless it has adequate brakes in good working order, and no house trailer weighing over 1,500 pounds unless it is so equipped. The section does not apply to a trailer or semi-trailer with a gross weight under 3,000 pounds if the axle weight of the towed vehicle does not exceed 40 percent of the sum of the rated axle weights of the towing vehicle. It also leaves out a list of towed machines when driven in intrastate commerce within New Hampshire and towed no more than 2 miles at one time: wood-sawing machines, log splitters, cement mixers, compressors, tar kettles, conveyors, two-wheel devices used by public utilities to carry up to six cables or poles, road rollers and sweepers, thawing devices and refreshment booths on wheels.

RSA 266:63 says every trailer or semi-trailer, farm vehicles included, must have in addition to the tow-bar or coupling a safety chain or cable to prevent breakaway. Each chain or cable must have an ultimate strength at least equal to the gross weight of the trailer and load, and be connected to both vehicles so the tow-bar cannot drop to the ground if it fails. Fifth wheel units, full trailers behind a dolly or fifth wheel, trailers towed by motorcycles and certain farm implements are left out. RSA 266:46 says a load that extends four feet or more behind the bed or body must show a red light or lantern at the extreme rear during lighting periods, and a red flag or cloth at other times.

Width, height and length

RSA 266:12 sets 102 inches as the width limit for a vehicle including its load. RSA 266:10 sets 13 feet 6 inches as the height limit including load, with a separate limit for manufactured housing transport. RSA 266:11 limits a single unit vehicle or bus to 45 feet including bumpers, a semi-trailer in a truck-tractor combination to 53 feet with conditions on any semi-trailer over 48 feet, and a semi-trailer or full trailer in a combination with two trailing units to 28 feet. See RSA chapter 266 on equipment, size and weight.

Weight

RSA 266:18-a covers highways other than the interstate. With a gross weight not over 73,280 pounds it allows 22,400 pounds per axle on three-axle single unit vehicles and on other vehicles with axles 10 feet or more apart, and 18,000 pounds per axle on axles less than 10 feet apart. It sets maximum gross weight at 33,400 pounds for a two-axle vehicle and 55,000 pounds for a single unit three-axle vehicle, or the weight formula result if greater. On the interstate, RSA 266:18 allows 20,000 pounds on axles more than 8 feet apart when gross weight is over 73,280 pounds. RSA 266:18-d covers additional certification and registration for higher weights.

Carrier rules

RSA 266:72-a lets the commissioner adopt as rules the federal motor carrier safety regulations in 49 CFR parts 107, 380 and 382 to 397, and says later federal amendments supplement those rules without further action. Drivers who operate only in intrastate commerce are subject to the medical examination, written test and road test of 49 CFR 391.31 to 391.49, and utility service vehicle drivers in intrastate service are exempt from the hours of service rules in 49 CFR part 395. The chapter read does not give a weight line for an intrastate carrier registration.